In petroleum and other pipelines, there exists a need to measure certain properties of the fluid, which generally is flowing.
In particular, a measurement of viscosity (either absolute or kinematic) is needed to:
(a) differentiate fluids, PA1 (b) detect the interface between two different fluids, PA1 (c) characterize pressure gradients in a pipeline for purposes of leak detection and locations, PA1 (d) determine when a change or interface between fluids occur, and PA1 (e) determine the required amount of dilution agent to meet the maximum viscosity limit set by the pumping power and pressure rating of the pipeline.
Currently available means for these measurements are complex, expensive, and sometimes unreliable. For example, viscous forces are sometimes measured by vibratory systems. For these means and most others, a bypass line is necessary to direct a fraction of the flowing fluid to the means of measurement. The bypass can become obstructed with waxes or other elements carried by the flowing fluid. In addition, the moving parts of such measurement means can create maintenance and calibration problems. Many pipeline operators take grab samples of the flowing fluid to determine density and viscosity, because the accuracy and reliability of the on-line means do not meet their requirements. The expense of the sampling procedure is obvious. In addition, the procedure deprives the pipeline operator of the ability to monitor and control the properties continuously and in real time.